A household contact of a Wollongong woman confirmed to have COVID-19 has been diagnosed as the number of people allowed in homes changes just one day before New Year's Eve.
NSW recorded 18 locally acquired cases of COVID-19 in the 24 hours to 8pm last night.
Of those cases, a woman aged in her 50s and a household contact of her, a woman aged in her 20s, were diagnosed overnight.
One of the cases from Wollongong and a northern Sydney case were first reported yesterday morning.
Dr Kerry Chant thanked the Wollongong community for going out in droves to get tested and reiterated the importance of getting tested if anyone had the mildest of symptoms or if they had been to venue a where the case visited between December 21 and December 27.
"We have seen in the past that the Wollongong community responds and we expect that to happen again," she said.
"Get tested if you have the mildest of symptoms."
Meantime, Premier Gladys Berejiklian has restricted the number of people allowed in a home to five.
For New Year's Eve in Greater Sydney, which includes Wollongong, Central Coast and Blue Mountains, household gatherings will be limited to five visitors including children; and the limit for outdoor gatherings will be reduced from 50 to 30.
Restrictions for the northern zone of the Northern Beaches remain the same but for the southern zone of the Northern Beaches household gatherings are limited to five visitors from within your zone including children.
All changes come into effect from midnight tonight and will be in place until further notice.
Premier Berejiklian encouraged people to limit non-essential gatherings over the New Year period where possible to further minimise the risk of transmission in the community.
She said the preferred advise was for people to stay at home, but if they did welcome people into their home then the limit was five and social distancing and hygiene methods should be adhered to.
There were 17,267 tests reported to 8pm last night, compared with the previous day's total of 16,329.
Of the 25 new cases, nine locally acquired cases are linked to the Avalon cluster with eight of these cases isolating for their full infectious period.
Six locally acquired cases, three adults and three children, all members of the same extended family, are linked to a cluster in Sydney's Inner West whose source is still under investigation. One of these cases was first reported yesterday morning.
Seven cases were acquired overseas and are in hotel quarantine.
This brings the total number of COVID-19 cases in NSW to 4,717 since the beginning of the pandemic.